Hi
I just got my 1st 4x5 camera on Ebay - crown Graphic and 4 fim holders. I have no expirience with 4x5 photography at all. Please explain me, what should i do with film after i shot it? Can i remove it from holders (in dark bag) and load holders with fresh film?
Where i can put film i just removed ? Is where special boxes/holders available? How should i deliver this film to photo lab?

I really hope your question is _not_ 'lame', because I asked the very same things not too long ago...

Yes, you can deffinitely reload holders using a changing (dark) bag.

As far as I have found out, no, there are no special film holders or boxes made for exposed film. I've search everywhere and asked lots of people. The stock answer is to use old film boxes. Unfortunately that only helps if you have old fim boxes laying around. If you know a lab that does 4x5, they may have some and be willing to give them to you. My alternative is to put the exposed film back into the film box. But at the bottom of the film stack and with an obvious seperator between the exposed and fresh film. When it ready to be taken to a lab or developed yourself, you can take out the exposed film using the changing bag.
My alternative to extra film boxes was film bags. I forget their proper name? They are just lastic bags, very heavy, and light proof. Take up almost no space when empty. The ones I found were 8x10 and work great. Just put the exposed film into the bag (inside the changing bag) and fold it over a couple of times. The 8x10 bag works good for that. When it comes out of the chaging bag, tape it closed. If you don't trust the bag (I don't), put the folded bag into another bag and fold that one. I got them from B&H I think and they were pretty cheap. I honestly don't remember, but something like 10 dollars for a package of five or so.
I also hope you've found out how to load the film holders? Notches to the upper-right when looking at the open film holder, dark slide open to the bottom, film inserted at the top. I hope I explained that right?
I'm sure others can add more. Especially if you have any other questions...